Sub panel for ev charger

[jjswan33]

I had the subpanel put in my garage, it’s only for the garage and outside the house. My main panel which is on the other side of the wall in the basement is just for inside the house.

But is it full? Does it have big loads already using most of that 200A if not then you are probably good.

The same 80% rule applies for your main breaker too, you shouldn't pull more than 160A continuous.

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[Airmoses]

I don't believe 4awg will fit in the terminals in the Wall Connector. There's no point in running 4awg with the added cost over 6awg. Further you have 4awg running to the panel to feed all of your loads.

6awg THHN or THWN is rated for 60A and 48A continuous on the 80% rule.

Only need to run 20 feet, so betweeen that and the 100 amp breaker not an expensive instal.

https://nassaunationalcable.com/pro...uNtIEAWrq0Fa2XfXOgA8uoYX_stQoyMBoCWCYQAvD_BwE

 

[240vPlug]

What about the main panel? What does that look like? Overloading your main panel is a code violation and could serious safety issues. Nothing else matters until you verify your main panel can support the additional load.

You can upsize the breaker for the sub panel IF 1) your main panel load calcs say it can support it AND 2) Your sub panel and the conductors feeding it are rated for the additional amperage.

If you feel like everything is good, then pull a permit with your local planning and permitting office and then have it inspected after. This will CYA if there is any problem or if you ever decide to sell the property.

Also, THHN ampacity depends on the temperature rating of the insulation. 90C #6 THHN is has a rated ampacity of 75 amps whereas 60C is only rated at 55 amps.

#6 NM-B aka Romex is actually 90C however because its not in conduit and because it can be run in hot attics and crawl spaces NEC says its limited to ampacity of 60C which is 55 amps. Now if you aren't confused already, many electricians will tell you they can round up the breaker to 60 amps because there is no 55 amp breaker...but technically 48 amps still exceeds the 80% rule. Needless to say you will see more often than not electricians putting in 6/2 Romex because well....try getting 4/2 or 4/3 Romex...its tough.

I did 90C #6 THHN in conduit for my Tesla chargers.

https://www.cerrowire.com/products/resources/tables-calculators/ampacity-charts/

Decent article on load calculation:
https://www.familyhandyman.com/article/electrical-load-calculation/

Please be careful folks..there is a lot at stake when it comes to your home electrical. Melting electrical panels, breakers, fires, etc. If your lucky your main breaker will just trip frequently to let you know things are not good.

 

[Airmoses]

So went to my my local electrical supply house and they sold me #6 NM-B they said it is all I need based on my needs as im running it in a wall and thru the garage crawl space to my panel. But I went to manufactures website and it says it’s 60C rated. Looks like I just blew $150.

https://www.encorewire.com/products/nm-b-copper.html

 

[Zoidz]

So went to my my local electrical supply house and they sold me #6 NM-B they said it is all I need based on my needs as im running it in a wall and thru the garage crawl space to my panel. But I went to manufactures website and it says it’s 60C rated. Looks like I just blew $150.

https://www.encorewire.com/products/nm-b-copper.html

Yeah, it’s technically rated at 90c (that’s what the B stands for) but NEC requires using the 60c ampacity rating. At 60c it is rated at 55 amps. Using the 80% rule for EV connections, you could use it at 44 amps, but you won’t find a breaker at that rating, so 40 amps would be the closest. You would charge at about 19-21 miles per hour at that rate.

 

[Davethadog]

First of all, this is #2 aluminum SER which is absolutely not the same as copper. Second, ev nerds are not the people to consult for any electrical advice.

 

[supernu8]

You can upsize the breaker for the sub panel IF 1) your main panel load calcs say it can support it AND 2) Your sub panel and the conductors feeding it are rated for the additional amperage.

This is good advice. Your subpanel and subpanel feed wire appear to be capable to swap up to a 100A breaker but it will depend on what loads you have going on in your main panel.

First of all, this is #2 aluminum SER which is absolutely not the same as copper.

OP photo shows MTW wire which is most defiantly copper.

Using the 80% rule for EV connections, you could use it at 44 amps, but you won’t find a breaker at that rating, so 40 amps would be the closest.

Not quite. 80% rule is for the load on the circuit not the breaker, beaker max is set by wire type.
With 6NM you can use a 50A breaker and set the EVSE to 40A charging

 

[ddimit]

Yeah, it’s technically rated at 90c (that’s what the B stands for) but NEC requires using the 60c ampacity rating. At 60c it is rated at 55 amps. Using the 80% rule for EV connections, you could use it at 44 amps, but you won’t find a breaker at that rating, so 40 amps would be the closest. You would charge at about 19-21 miles per hour at that rate.

Most end terminations, Panels/breakers. EV chargers are only rated to 60/75 degree so having wire rated above doesn't make a difference NEC will downrate to end terminations

 

[Mathme]

I' no electrician, but you already have a 230v outlet that you rarely use (for your tablesaw). Why not mount tap your EV charger into that outlet, then unplug the EV charger on the rare occasions you're using the tablesaw, etc.?

 

[Airmoses]

Most end terminations, Panels/breakers. EV chargers are only rated to 60/75 degree so having wire rated above doesn't make a difference NEC will downrate to end terminations

why does telsa require 90c rated then, would rather spend the money on new wire and play it safe

 

[Supratachophobia]

Could be load calcs would not allow for more than 60 amps. Also depends on the size of your load center and how many other loads you have.

If you have a 200 amp service your continuous load should not be more than 160amps at any given time. If you exceed the capacity of your panel you could run into serious safety issues.

Correct, the busbar rating on a 200amp panel is usually only 225. I don't recall off the top of my head how they calculate sub panelS that are breaker fed or use pass through lugs.

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